Barbecue grills enjoy a continuing popularity for outdoor cooking. A perennial problem is the difficulty in cleaning the grill surfaces on which food is placed. These surfaces tend to become encrusted with burned grease and bits of food. Another problem associated with barbecue cooking is that some types of food tend to crumble when cooked on the thin metal rods which comprise the conventional type of barbecue grill. This problem is especially troublesome in connection with types of food that have recently become more popular among health conscious people. These foods include fish and tofu, which are barbecued to reduce consumption of red meat. Conventional barbecue grills also are limited in that they do not provide any means for cooking diced food or steaming vegetables.
U.S. Pat. No. 4,632,089, granted Dec. 30, 1986, to Lawrence Wardell, discloses a barbecue grill having hollow tubular members instead of the conventional solid metal rods. Water is circulated through the hollow tubular members to cool the grill and reduce the necessity to clean it. The water is supplied to the members through a circular supply tube extending around the periphery of the grill. The water may be supplied from an independent water source or as part of a closed circulating system. The circulation of the water is described as increasing cooking efficiency because of increased heat and steaming action from condensation that occurs during cooking.
U.S. Pat. No. 4,798,132, granted Jan. 17, 1989, to H. W. Chan, discloses a serpentine tubular grid for cooking over a fire. A heat exchange medium, such as water or Freon (trademark) is circulated through the tubing during the cooking to reduce the tendency of the food to stick.
U.S. Pat. No. 1,233,216, granted Aug. 28, 1917, to C. O. Thomas, Jr., discloses a portable field kitchen with nesting members. The kitchen includes a tank and a tubular grate through which water from the tank circulates. Boilers and roasting pans are placed on the tubular grate and/or over a fire for cooking. When the cooking has been completed, the water can be used for cleaning.
U.S. Pat. No. 70,077, granted Oct. 22, 1867, to G. Dewey, discloses a reservoir cooking stove. The stove includes a boiler, an oven, and a hollow grate in the oven. The grate is in communication with the boiler for circulating heated water therethrough to cook food in the oven or heat a room.
U.S. Pat. No. 1,294,159, granted Feb. 11, 1919, to T. E. Potts, discloses a gas broiler having a tubular grate through which combustion gases circulate to heat the grate. Potts states that soot and burned grease tend to collect on the grate, which are therefore removable for cleaning. U.S. Pat. No. 1,775,790, granted Sept. 16, 1930, to J. T. Tawlks, discloses a furnace grate bar that is cooled by circulation of water through a pipe coil embedded in the bar. Tawlks states that the bar will require practically no cleaning. U.S. Pat. No. 3,818,818, granted June 25, 1974, to J. O. Hice, Sr., discloses a cooking chamber having a cooking coil through which a coolant is circulated to rapidly reduce the temperature in the chamber. U.S. Pat. No. 4,224,862, granted Sept. 30, 1980, to B. E. Liebermann, discloses a warming oven having a coiled pipe within the walls of each of a plurality of support shelves for radiating heat.
U.S. Pat. No. 3,982,476, granted Sept. 28, 1976, to J. S. McLane, discloses barbecue cooking apparatus with a corrugated perforated food platform. U.S. Pat. No. 4,197,791, granted Apr. 15, 1980, to J. L. Vieceli et al. discloses an electric steamer for simultaneously steaming a frankfurter and a frankfurter bun in which the frankfurter rests on a V-shaped perforated rack.
U.S. Pat. No. 3,493,726, granted Feb. 3, 1970, to W. M. Bardeau, discloses a coated nonstick grilling surface.
U.S. Pat. Nos. 1,432,335 granted Oct. 17, 1922, to A. L. Howard, and No. 3,246,644, granted Apr. 19, 1966, to C. F. Peterson, disclose water heaters having tubular elements which extend over a heat source and through which the water circulates. U.S. Pat. No. 3,472,221, granted Oct. 14, 1969, to A. T. Stevens, discloses a melting grid for melting thermoplastic materials in which a heating fluid circulates through a zigzag coil.